This application requests a BD LSRII flow cytometric analyzer for an existing shared resource Cell Analysis Facility (CAF) at the University of Washington. The CAP was established by the Department of Immunology in 1991 and has been in continuous operation since that time. During the past year, research personnel working in the laboratories of more than 100 principal investigators from 28 different departments in the School of Medicine and 8 other Schools or Colleges and the Regional Primate Center used the facility. These investigators span an extraordinarily diverse range of biomedical and biological research interests and enjoy robust funding from the NIH and other federal agencies. This application documents the limitations of our current facility in meeting the needs of these investigators for access to contemporary flow cytometry instruments and how an LSR II analyzer would allow us to meet these needs.